What Exactly Is ‘Heat Index’?

It's hot. But for some reason, it's more than hot. You step outside and it feels like you're stepping into a war, wet blanket. You've heard the phrase 'It's not the heat, it's the humidity'? Well, we don't use Humidity anymore. Now we use Heat Index.

So what exactly is a Heat Index?

Well believe it or not, it has to do with your sweat! Or if you prefer, your perspiration. According to the National Weather Service Website, when the Atmospheric Moisture Content is high (yep, another official way of saying it's "thick"), the rate at which we sweat...uh, I mean perspire...decreases. In effect, our air conditioner slows down. So the human body feels warmer in humid conditions. And by the way, the opposite is also true, when the relative humidity drops, we perspire more and our body cools better.

So basically, the Heat Index is a more precise figure than Relative Humidity. At least that's what the weather folks say, and who am I to argue. So maybe there is something to "Yeah, it's 110 degrees in Phoenix, but it's a dry heat."

All I really know is this: Be careful out there, stay hydrated and we'll long for 'Heat Index' come about February.